Angiogenesis is a fundamental process by which new capillaries are formed from existing blood vessels. This process plays important roles in physiological events such as formation of the corpus luteum, development of the embryo and wound healing, including recovery from both myocardial ischemia and peptic ulcer (1). Unregulated growth of blood vessels can contribute to tissue injury in a large number of diseases such as arthritis, diabetes, and tumor progression (2). Endothelial cells are normally quiescent and are activated during the angiogenic response. Upon stimulation, endothelial cells can degrade their basement membrane and proximal extracellular matrix, migrate directionally, then divide and organize into functional capillaries invested by a new basal lamina (3).
There is a growing body of evidence demonstrating that the angiogenic switch is regulated by the net balance between positive and negative regulators of new capillary growth (2). Persistence of neovascularization requires a pro-angiogenic environment, with the expression of angiogenic factors outweighing that of angiostatic factors. A range of peptides can influence this balance, including mitogenic factors such vascular endothelial growth factor (VEGF) (3), nonmitogenic factors (selected cytokines, CXC chemokines), and internal peptide fragments of angiostatin and endostatin (3). Certain eicosanoids also have potent biologic actions on vascular endothelial cells. In rabbits, PGE2, PGR2xcex1, and prostacylin (PGI2) stimulate angiogenesis where prostaglandin E series, in particular PGE1, is most potent. PGE2 is a potent inducer of VEGF expression in synovial fibroblasts. In addition to its known vasodilator and antiplatelet properties, PGI2 can also induce VEGF gene expression and protein synthesis (4).
It was recently reported that 12-lipoxygenase activity and one of its products, 12(S)-HETE, is required for angiogenic responses (5), and that P450-derived 12R-HETE stimulates angiogenesis via NF-kB (6). The cyclooxygenase-2 (COX-2) gene in endothelial cells is rapidly upregulated by several growth factors as well as inducers of angiogenesis (7). Along these lines, results using three different endothelial cell models show that COX-2 is an essential component of angiogenesis, at least in vitro (8). Nonsteroidal anti-inflammatory drugs such as aspirin (ASA) have been implicated in the prevention of certain cancers such as lung and colon cancer (9, 10) that might be related to ASA""s ability to reduce angiogenesis (7).
A need therefore exists, for compositions and methods to prevent angiogenesis that are directed toward the disease process, such that angiogenesis is prevented or inhibited physiologically. A need also exists for compositions and methods that induce angiogenesis in tissue that is lacking the requisite or essential physiological requirements for sustainability.
Proliferative states such as chronic inflammation, ischemic diseases and cancer are often accompanied by intense angiogenesis, a highly orchestrated process involving vessel sprouting, endothelial cell migration, proliferation and maturation. Aspirin-triggered lipoxins (ATL), the 15R enantiomeric counterparts of lipoxins (LXs), are endogenous mediators generated during multicellular responses that display potent immunomodulatory actions. Surprisingly, it has been discovered that LXs, ATLs, and more specifically, the ATL stable analogs, 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (denoted ATL-1), LXA4, 15-epi-LXA4 and 15-R/S-methyl, LXA4 are potent inhibitors of angiogenesis. For example, ATL-1, LXA4, 15-epi-LXA4 and 15-R/S-methyl, LXA4 each inhibited endothelial cell proliferation in the 1-10 nM range by xcx9c50% in cells stimulated with either vascular endothelial growth factor (VEGF) at 3 ng/ml or leukotriene D4 (10 nM). In addition, ATL-1 (in a 10-100 nM range) inhibited VEGF (3 ng/ml)-induced endothelial cell chemotaxis. In a granuloma in vivo model of inflammatory angiogenesis, ATL-1 treatment (10 xcexcg/mouse) reduced by xcx9c50% the angiogenic phenotype, as assessed by both vascular casting and fluorescence. Together, these results identified a novel and potent previously unappreciated action of aspirin-triggered 15-epi-LX.
In one aspect, the present invention pertains to methods for the prevention, reduction or inhibition of angiogenesis. The method is accomplished by the administration of an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof. As a consequence of the action of the therapeutic agent, angiogenesis is prevented or inhibited in the subject.
In another aspect, the present invention also pertains to methods for the prevention or inhibition of angiogenesis. The method is accomplished by the administration of an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof. As a consequence of the action of the therapeutic agent, angiogenesis is prevented or inhibited in the subject.
In still another aspect, the present invention pertains to methods for the prevention or inhibition of solid tumor tissue growth undergoing neovascularization in a subject. The method is accomplished by the administration of an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof, to a subject in need thereof.
In another aspect, the present invention pertains to methods for the prevention or inhibition of solid tumor tissue growth undergoing neovascularization in a subject. The method is accomplished by the administration of an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
In yet another aspect, the present invention is directed to methods to inhibit or prevent neovascularization from occurring in a subject. The method is accomplished by the administration of an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
In yet another aspect, the present invention is directed to methods to inhibit or prevent neovascularization from occurring in a subject. The method is accomplished by the administration of an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
The invention is also directed to methods for treating a subject in which neovascularization is occurring in retinal tissue. The neovascularization in the retinal tissue can be prevented or inhibited by administering an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
The present invention is further directed to methods for treating a subject in which neovascularization is occurring in retinal tissue. The neovascularization in the retinal tissue can be prevented or inhibited by administering an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
The invention is further directed to methods for treating a subject for restenosis in tissue wherein smooth muscle cell migration occurs following angioplasty. The restenosis can be prevented or inhibited by administering an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
The invention is directed to methods for treating a subject for restenosis in tissue wherein smooth muscle cell migration occurs following angioplasty. The restenosis can be prevented or inhibited by administering an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
In still another embodiment, the invention pertains to methods of reducing blood supply to tissue required to support new growth of the tissue in a subject. This reduction or elimination of new undesired growth of tissue can be accomplished by the administration of a composition comprising an effective amount of LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
The invention further pertains to methods of reducing blood supply to tissue required to support new growth of the tissue in a subject. This reduction or elimination of new undesired growth of tissue can be accomplished by the administration of a composition comprising an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof.
Further, the present invention pertains to methods for the prevention, diminishment or inhibition the production of new vessels in a subject associated with or stimulated by the production or release of VEGF. The method is accomplished by the administration of an effective amount of a therapeutic agent, including LXA4 and analogs thereof, such as 15-R/S methyl, LXA4, and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, to a subject in need thereof. Alternatively, an effective amount of an aspirin triggered lipoxin (ATL) (15-epi-LXA4, such as 15-epi-16-(para-fluoro)-phenoxy-lipoxin A4 (ATL-1)), and pharmaceutically acceptable salts, esters, amides or prodrugs thereof can be utilized. As a consequence of the action of the therapeutic agent, growth of new vessels associated with the production of VEGF is prevented or inhibited and thus the growth of endothelial cells in the subject. For example, VEGF is associated with tumor genesis, lymphoangiogenesis and proliferative disorders. The invention therefore, can be used to inhibit, reduce or prevent metasasis of tumors.
Surprisingly, configurational isomers of LXA4, LXA4 analogs and ATL analogs, LXB4 and LXB4 analogs and pharmaceutically acceptable salts, esters, amides or prodrugs thereof, provide the opposite effects with regard to revascularization of tissue by the above-identified compounds of the invention. That is, it has been surprisingly discovered that LXB4 and LXB4 analogs have the ability to stimulate regeneration and ingrowth of vascular or epithelial tissue in tissues that are in need of such stimulation. This is especially important in tissue grafting, tissue engineering and prosthetic group sites of attachment.